Nick Saban says soph. QB Tua Tagovailoa is suffering from a sprained knee, is wearing a brace at practice, but has taken every rep this week.Saban also confirms CB Trevon Diggs (foot) is going to be out "an extended period of time," doesn't expect him back this season.

I've never sprained a knee but I've sprained an ankle. If they hurt the same amount then it could be uncornfortable. Of course, I didn't have a training staff available to me.

I sprained mine at the Clemson/Wofford game in 2011 walking to the stadium. Someone cut in front of my son and he cut in front of me. When I took evasive action I hit a curb cutout. It wasn't bad that day, just a little tight. The next day it was sore. Monday morning it was twice the size it should be and I couldn't put any pressure on it. Took me about a month before it finally quit hurting.